The present invention, in some embodiments thereof, relates to an ultrasonic digitizer and host.
Currently there are products which have a digitizer integrated into a host, whether a laptop or desktop computer, or in a more generalized form: a host. Furthermore there are acoustic digitizers provided as external peripherals that may be added to the host, as add-on's.
The suggestion is known to embed an ultrasonic receiver inside a mobile phone or a “smart phone”.
There are numerous technologies, that support digitizing, particularly of handwriting:                1) RF tablets: companies, such as Wacom, Acecad, and N-trig, use a pad with an antenna to emit RF energy to a stylus that is located above the pad. This is unsatisfactory since a computer needs a retractable pad, and this makes usage cumbersome. A built-in RF solution has no advantages in contrast with an add-on solution having the same properties.        2) Optical sensor: Anoto is the owner of a technology which uses a special paper with imprinted dots. The stylus has a camera to decode its location based on the dots it sees. In this technology, there is no need to embed the receiver inside the host since it uses standard RF protocols such as Bluetooth to communicate with its host. However, the special paper, bulkiness of the pen and the price, are limiting factors for this technology.        3) Ultrasonic sensor: there are several companies that use ultrasonic TOA measurement to estimate a location of a stylus. Pegasus (Pegatech), Navisis, Virtual ink and others are examples. The enabling technology for these products uses acoustic pulses for measuring the TOA. Acoustic technology has advantages in relation to the previous two technologies described above, namely it can operate on any surface and can allow 3/D applications. However, the known art has inter alia the following disadvantages:                    a. Inferior accuracy and resolution            b. Size of receiver            c. Susceptibility to ultrasonic noise            d. Susceptibility to other users in the vicinity using the same technology            e. Relatively low sampling rate            f. Delay between writing and digital representation                        
On the other hand, there are benefits to having handwriting digitization on a computer, for example the following abilities may be obtained:                1) Transferring handwritten notes to a digital format.        2) Controlling the computer (the stylus being used as a mouse).        3) Direct digital input for sketches and drawings.        4) Notes insertion to existing documents, in the same way one can write notes on a printed document.        5) Form filling.        6) 3/D applications.        
The following documents were published after the priority date of the present application and thus their prior art effect on the present claims depends on the specific jurisdiction.
WO2008018757 discloses a position-tracing-signal generating apparatus and an input system including a position-tracing input apparatus for inputting information by tracing the position of the position-tracing-signal generating apparatus. The position-tracing-signal generating apparatus is capable of inputting accurately information on the position-tracing by emitting a ultrasonic-wave signal through a guide path formed between a guide part and a ultrasonic-wave signal generating unit in only a paper surface direction irrespective of usage of the position-tracing-signal generating apparatus by user. In addition, according to the position-tracing-signal generating apparatus, a plurality of ultrasonic-wave generating members are provided in the ultrasonic-wave signal generating unit, and the ultrasonic-wave generating members sequentially generate ultrasonic-waves in a predetermined time interval calculated based on separation distances between the ultrasonic-wave generating members so that the ultrasonic-wave signal can be amplified through superposition of the ultrasonic waves generated by the ultrasonic-wave generating members. Accordingly, the position-tracing-signal generating apparatus can also stably transmit the ultrasonic-wave signal to an ultrasonic-wave signal receiving sensor disposed at a long distance.
WO2008048036 teaches a 3D position tracking method and apparatus. The 3D position tracking method and apparatus measures a 3D position of a signal generator by using distances between a signal generator and ultrasonic signal receivers calculated by using differences between a time at which an ultrasonic signal is generated by the signal generator and times at which the ultrasonic signal is received to the ultrasonic signal receivers that are disposed at predetermined intervals to receive the ultrasonic signal, and distances between the ultrasonic signal receivers. Accordingly, a 3D position of a moving object in a 3D space can be accurately measured without excessive costs, and a 3D position tracking method and apparatus as described therein can be applied to a 3D mouse, a 3D pointer, a 3D video game input device, and the like.